3570 Series the range springs, bias springs, and spring retainer are correct for the application. Refer to table 4 or consult your Fisher sales office or sales representative. If the springs and spring retainer are correct, and careful adjustment of the unit does not produce smooth and satisfactory operation, check the following points. Key numbers used in this procedure are shown in figure 11 except where indicated. Figure 2 shows part locations.
F 40A8972-B/DOC
1. Clean out the primary orifice on each relay by depressing the clean-out plunger. The plunger is located in the orifice assembly (key 29S). This operation runs a fine wire through the orifice to clear the hole.
E
R
EXHAUST
D C
2. Check the nozzle (key 29Q) of each relay for plugging. To clean, swing the flapper (key 12) away from the nozzle by loosening the screw that holds the flapper in place.
A 1
B
CAUTION
OUTPUT
G
CLEAN-OUT PLUNGER SUPPLY NOTES: 1 OUTPUT PORT IS SHOWN 90 DEGREES TO THE FRONT OF ACTUAL LOCATION W0700-1/IL
A–SUPPLY PRESSURE AREA B–RELAY OUTPUT PRESSURE VALVE C–EXHAUST VALVE D–RELAY OUTPUT PRESSURE AREA E–DIAPHRAGM HEAD ASSEMBLY F–NOZZLE G–RELAY RESTRICTION PLUG ASSEMBLY R–FIXED RESTRICTION
Figure 10. Sectional View of a Typical Relay
D Disconnect any operating lines providing air pressure, electric power, or a control signal to the actuator. Be sure the actuator cannot suddenly open or close the valve. D Use bypass valves or completely shut off the process to isolate the valve from process pressure. Relieve process pressure on both sides of the valve. Drain the process media from both sides of the valve. D Vent the power actuator loading pressure and relieve any actuator spring precompression. D Use lock-out procedures to be sure that the above measures stay in effect while you work on the equipment.
The relays used in Type 3570C and 3570PC positioners use a locknut (key 29P, figure 12) on the nozzle (key 29Q, figure 12). If the nozzle is rotated when the locknut is tight, damage to the relay diaphragm will result. Always use a wrench on the nozzle to prevent it from turning while loosening or tightening the locknut. Unscrew the nozzle and run a fine wire through it. Do not enlarge the hole. Also check the surface of the flapper for any accumulation of dirt or foreign materials. 3. Check the bellows assembly for damage, misalignment, or leakage. Also check all gasketed joints for leakage. Use soap solution for leak detection. 4. Check the beam for damage, binding or rubbing against stationary parts. Check the flexure strip screws (key 17) for tightness. 5. If the positioner operation has improved, refer to the adjustment procedures. 6. If the positioner operation does not improve, go to step 7. 7. Unscrew the three machine screws (key 31) from each relay and remove the relays.
Troubleshooting
8. Check the two relay diaphragms (keys 29F and 29K) for holes or cuts. Note that the larger of the two diaphragms has five holes in it: four holes are for the flange screws and one permits the flow of air from the primary orifice to the chamber between diaphragms.
If the positioner causes sluggish or erratic operation or the malfunctioning of the actuator, first, be certain that
9. Check the relay valve plug (key 29B) for nicks, cuts, or dirt. Also check both inlet and exhaust ports.
17